This mortgage recast calculator estimates a new principal-and-interest payment after a lump-sum principal prepayment when a servicer allows recasting. Rate and loan identity usually stay the same. Confirm eligibility and fees with your servicer.
A mortgage recast, sometimes called reamortization, keeps your existing note rate and remaining term while rebuilding the amortization schedule on a lower balance. That is different from a refinance, which replaces the loan and can change the rate, term, and closing costs. It is also different from simply sending extra principal without asking for a recast, which usually shortens the payoff timeline while the contractual payment stays the same. This mortgage recast calculator keeps those three paths visible side by side.
Explore more housing tools in the mortgage and real estate category. Build a standard payment on the mortgage calculator, estimate settlement fees on the closing costs calculator, model a tax and insurance payment spike on the escrow shortage calculator, and compare a generic amortizing note on the loan calculator.
What a recast changes and what it does not
After a qualified lump-sum curtailment, many servicers can reamortize the remaining balance over the months left on the note. The interest rate stays the same. The maturity date usually stays the same. The monthly principal and interest payment falls because the same rate and term now apply to a smaller balance. Escrow amounts for taxes and insurance are separate and can still move after an escrow analysis even when the principal and interest line drops.
Not every loan allows a recast. Investor guidelines, minimum lump-sum thresholds, and fees vary. Confirm eligibility with your servicer before treating a Multicalify estimate as an approval.
How to use this mortgage recast calculator
- Enter the current unpaid principal balance.
- Enter the note interest rate and months remaining.
- Enter the lump sum you plan to apply to principal.
- Enter any recast fee the servicer quotes.
- Optionally enter a refinance comparison rate and refinance closing costs.
- Read the recast payment, keep-payment payoff months, refinance payment, and fee break-even months.
How Multicalify calculates the recast payment
New balance equals current balance minus the lump sum. The recast payment is the standard EMI amortization of that new balance at the same annual rate over the same months remaining. The tool also computes the current payment on the old balance for comparison. Monthly savings equal current payment minus recast payment. Fee break-even months equal the recast fee divided by monthly savings when savings are positive, rounded up.
Keep payment versus refinance comparison
If you apply the lump sum but keep the old payment, Multicalify estimates how many months the lower balance takes to clear at that higher contractual payment. That path usually saves more total interest than a recast because you are overpaying relative to the new amortizing payment. The refinance column amortizes the reduced balance at the comparison refinance rate over the same remaining term and shows a separate cost break-even against refinance fees. Refinance only wins in this sketch when the rate drop and payment savings outlast the upfront costs before you sell or pay off.
| Path | What changes |
|---|---|
| Recast | Same rate and remaining term, lower payment on new balance |
| Prepay, keep payment | Same contractual payment, fewer months to payoff |
| Refinance | New rate (and often new costs), payment rebuilt on new balance |
Recast versus refinance versus extra principal
Choose a recast when you want lower required cash flow each month and you like your existing rate. Choose extra principal without a recast when your goal is faster payoff and lower total interest while you can still afford the current payment. Choose a refinance when a meaningfully lower rate is available and the closing costs break even inside your expected ownership window. Closing cost planning belongs on the closing costs calculator, not inside the recast EMI itself.
Escrow shortages are a different problem. A tax or insurance catch-up changes the escrow portion of the total payment and does not reamortize principal. Send that question to the escrow shortage calculator.
When a recast fee is worth paying
Servicers often charge a flat recast fee. Divide that fee by the monthly payment reduction to see how many months you need to keep the loan before the fee is recovered in cash-flow terms. If you expect to sell or refinance again soon, the fee may not be worthwhile even when the new payment looks attractive. If you need lasting payment relief and will keep the loan for years, the break-even can arrive quickly.
Cash-flow goals versus interest savings
Recasting optimizes for a lower required payment. Keeping the old payment after a curtailment optimizes for interest savings and earlier payoff. Households sometimes recast after a large bonus, inheritance, or home sale proceeds when they want breathing room rather than the fastest payoff. Others keep the payment and treat the lump sum as a pure acceleration tool. Run both Multicalify columns before you decide which request to make.
Recast mistakes homeowners make with large prepayments
- Assuming every servicer will recast any lump sum without a minimum or fee
- Comparing a recast to a refinance without including refinance closing costs
- Expecting escrow taxes and insurance to fall when only principal was paid down
- Using a new purchase mortgage calculator result as if it were a recast schedule
- Ignoring that keeping the old payment after a lump sum often beats a recast on total interest
Limitations and YMYL disclaimer
Results are educational estimates only. They are not credit offers, servicing commitments, or financial advice. Recast eligibility, fees, investor rules, and timing vary by lender. Refinance assumptions can miss points, credits, and underwriting changes. Confirm final numbers with your servicer or loan officer before you move large sums.
Related calculators
Start from a clean payment on the mortgage calculator, then return here for lump-sum redesigns. Estimate refinance or purchase fees on the closing costs calculator, review escrow payment spikes on the escrow shortage calculator, and compare a generic amortizing schedule on the loan calculator. The full set lives under mortgage and real estate.
Deciding whether to request a recast
Estimate the new payment, ask the servicer about fees and timelines, and keep enough cash reserves after the lump sum. Read mortgage recast vs refinance if you are still choosing a path.
Recast versus refinance break-even thinking
If your rate is already competitive, a low-fee recast can beat refinance closing costs. If rates are meaningfully lower elsewhere, model refinance break-even separately instead of forcing a recast comparison.
Related: mortgage recast vs refinance · Mortgage Calculator.